(a) Technical Field
The present invention relates to a solvent-free polyurethane-based artificial leather having the texture of human skin, and particularly to artificial leather comprising soy protein isolate and solvent-free polyurethane resin, where the use of soy protein isolate provides a higher water content than that of the conventional artificial leather to improve sensitivity properties such as tactile sensation and the use of the solvent-free polyurethane resin provides higher heat resistance and better mechanical properties than those of the conventional artificial leather, without the use of an organic solvent, and thereby maintains clean indoor air.
(b) Background Art
Leather can be generally divided into natural leather and artificial leather. Because natural leather is obtained by processing the leather of animals, it is usually high in price due to limited output. Continuous processing of natural leather is impossible, and color variation and quality uniformization can also be difficult.
In contrast, artificial leather can be obtained by using fabrics such as non-woven fabrics or woven fabrics. However, artificial leather is still inferior to natural leather in sensitivity properties such as tactile sensation.
Conventional artificial leather is generally prepared by using a polymer or synthetic materials, is often uncomfortable, cold and slick to the touch, causes eye fatigue due to reflected light, and produces an unpleasant feeling because of unabsorbed sweat. Thus, conventional artificial leather is inferior to natural leather in sensations such as tactile sensation. In particular, due to its low water absorptive properties, artificial leather can be sticky as a result of humidity produced by the human body or from the surroundings. Artificial leather has not been satisfactory to meet the high quality demands by customers in color, gloss, processability, design and tactile sensation.
Various processes have been disclosed for the preparation of artificial leather in an attempt to meet the customer needs. For example, Korean Patent No. 10-0581330 discloses artificial leather prepared by using a porous structure of solvent-free polyurethane, which is superior to the conventional artificial leather in mechanical property, anti-yellowing and chemical resistance, but showing insufficient sensitivity properties such as tactile sensation. Korean Patent No. 10-0706403 filed by the present inventors discloses artificial leather comprising pulverized silk proteins and polyvinyl chloride resin. Although this artificial leather is superior in sensitivity properties, the production costs are too high for commercial application due to the use of expensive silk.
Most of the conventional polyurethane-based artificial leather polyurethane resin has been manufactured into one-component type. The one-component resin is a “polyurethane-organic solvent solution” comprising linear polymer prepared by polyaddition of diisocyanate and the same molar amount of polymer diol along with chain extender, and organic solvent such as DMF (N,N-dimethyl formide), MEK (methyl ethyl ketone), TOL (toluene) as a main ingredient. However, such artificial leather prepared by using an organic solvent produces odors and is an endocrine disruptor due to the volatility of the organic solvent.
Accordingly, there has been an increasing need for artificial leather that is superior in sensitivity properties such as tactile sensation as well as heat resistance and mechanical property in the fields of artificial leather manufacture, furniture industry and the automobile industry.
As a result, the present inventors have found that it is necessary to increase the water absorptive power of artificial leather in order to improve the sensitivity properties of natural leather such as tactile sensation.
The instant invention is directed to providing optimum content of ingredients and an application method for applying soy protein isolate to solvent-free polyurethane resin, and to minimizing the odor-production of artificial leather by solvent-free polyurethane resin instead of organic solvent.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.